Study of phase transformations in Spheroidal Graphite Cast Iron subjected to quenching and partitioning

Abstract

Iron alloy samples were submitted to a quenching and partitioning heat treatment. Samples were austenitized at 880 °C for two hours, quenched at 150 °C and kept at this temperature for 30 seconds, and finally re-heated at 280°C during time intervals between 5 and 90 minutes for partitioning. The microstructural evaluation was performed with dilatometry, SEM, optical microscopy, and X-ray. The experimental results showed a maximum peak in the percentage of retained austenite. The microstructure obtained was compared with that resulting from the austempering of the same alloy at 280 °C. It was observed that the microstructure component after both treatments is similar, although the microstructure of Q&P is thinner. Accordingly, the hardness after Q&P heat treatment is greater than that of ADI austempered at the same partition temperature.